The designs realized during the printing of fabrics are a result of superimposing, one on top of another, complimentary parts of the design, each being printed in its own color. This printing operation must be carried out with the greatest precision possible in order to avoid misalignment in the finished design. In general, the machine for printing such designs includes a bed upon which a conveyor belt advances intermittently, with the belt being moved through spaces of exactly the same lengths for moving the fabric to be printed, which fabric is attached to the belt. A plurality of printing screens are situated above the conveyor belt and are connected to movement devices which control the descending and ascending movement of the screens, which devices also cause the screens to pause when they are in their lower and upper positions. The movement of the screens is synchronized with the movement of the conveyor belt so that when the conveyor belt is stopped, the screens are held in their lower position for causing printing of the complimentary parts of the design.
From the point of view of the machine construction, the screen movement does not present any significant problem. However, this is not the case with respect to the conveyor belt. Since the conveyor is of rather large dimensions and consequently of considerable mass, the mechanisms controlling the intermittent advancing movement of the conveyor belt are necessarily rather complex and of considerable bulk in order to permit rapid intermittent advancing of the conveyor belt so that rather rapid printing can be achieved without exceeding the very limited error tolerance in the advancing movement length necessary for design alignment.
In fact, with conventional machines of the type described above, it frequently happens that the intermittent advancing movement of the conveyor belt cannot be controlled with the necessary degree of precision, so that the required registration or positioning of the individual parts of the finished design is not achieved, whereby the final printed design lacks the required degree of quality and thus results in an undesirable aesthetic effect which, in many instances, makes the printed fabric substantially worthless. Further, machines of this type do not, in all cases, result in the desired homogenity of the different colors, whereby the printed design on the fabric is of inferior quality.
Machines for printing fabrics employing multiple colors in the fabric design have also normally involved complex drive devices which are extremely costly and also require substantial repair, which further increases the overall cost of the finished fabrics by substantially increasing the loss of valuable production hours.
Thus, the present invention relates to improvements in a fabric printing machine and, in particular, to an improved control mechanism for controlling the intermittent advancing movement of the conveyor belt with sufficient precision to permit proper alignment of the complimentary parts of the printed design, which control mechanism is also dependable and economical, and can be composed from standard components which are generally available.
Other objects and purposes of the present invention will be apparent to persons acquainted with machines of this general type upon reading the following specification and studying the accompanying drawings.